Process to lower the vitrifying-point of ceramic substances.



UNITED STATES PATENT OFFICE.

, BOTHO SCHWERIN, 0F FRANKFORT-ON-THE-MAIN, GERMANY, ASSIGNOR TO GESELL SCHAFT FOR ELEKTRO-OSMOSE' M..B. I-L, FRANKFORT-O'N-THE-MAIN, GERMANY,

A. CORPORATION.

PROCESS TO LOWER. THE VITBI-F'YING-POINT OF CERAMIC SUBSTANCES.

No Drawing.

To all whom it may concern:

Be it known that I, BOTHO SCHWERIN, a subject of the German Emperor, residing at Frankfort-on-the-Main, Germany, have invented certain new and. useful. Improvements in Processes to Lower the Vitrifying- Point of Ceramic Substances, of which the following is a specification.

There are certain materials, such as soapstone, steatite and other similar silicates of magnesia, which deform and vitrify at approximately the same temperature and any attempt to fire objects formed of-these materials after the roaterials have been finely ground is found impracticable, for the reason that the material forming the objects does not'vitrify or become densebefore deforming and the objects do not keep their form after the deformation has begun. To overcome this difliculty, it hasbeen the usual practice to lower the vitrifying points of the above-named materials by-the addition of kaolin and similar substances which, in

conjunction with the original material, forms. a composition which vitrifies at a lower temperature. This ractice is attended with the lowering o the vitrifying oint, so that it is possible to preserve the orm of the objects, inasmuch as the same do not deform, but on the other hand, these objects naturally have the drawback of not being composed entirely of the pure, original material. It is found that objects so prlepared have lostmore or less of their fo mer characteristics possessed before the addition of the binding material.

. which may be mentioned, for instance, the

said articles from the pure material without.

any foreign substance being mixed therewith. f

v The method of procedure in the present invention is as follows: The raw material is Specification of Letters Patent.

This drawback has many different effects among "the suspension is drawn ofl, put in an electro-osmotical machine and exposed to the action of an electric current whereby the material is deposited on the anode in rela tively dry form, as set forth in my United States Patent No. 993,888. The deposited material is then taken from the anode and mixed with the necessary amount of water for the forming or casting of objects, after which the objects may be burned in the wellknown manner.

The results of the process just set forth will be described in connection with the following table:

Percentage of water absorbed.

No. 2. Degrees centigrade.

- Seger cone. No. 4. Af- No. 5. At-

ter standing l I'SihII ling 72 hours. 120 hours.

No. 8. Untreated.

represent the percentages of water absorbed by specimens made according to the present invention, Whereas column 3 indicates the percentage of water absorbed by the originalv material which had been formed ready for the burning without having been sub- Patented Dec. 15, 1914.

Application filed February 27, 1913. Serial No 751,140.

jected to the process disclosed herein. Referring to column 3, it will be seen that objects made from the pure, untreated material, which in this instance was steatite, will i 5 absorb water irrespective of the temperature at which they are burned, except at the temperature of 1530", at which temperature ob-' jects deform. The fourth column shows the percentage of water absorbed by specimens made from the material treated according to the present invention where the particles I were in suspension for 72 hours before being a collected. a It will be noted that the specimen which was burned at a temperature of 1350 centigrade absorbed 4 1000 of 1% of water, whereas the specimen made from the untreated material at the same temperature absorbed 12.55% water. The fifth column shows the percentage of water absorbed by specimens which were made from material treated according to the present invention where the material before collection in the electro-osmotic machine had stood for 120 hours. It will'be seen that the specimen so made, which was burned at the temperature of 1350 'centigrade. had zero absorption of water. See column 5. It will further be noted that specimensmade from materials treated according to the present invention could be burned without deforming at such a temperature that the burning would prevent absorption of water. Thus'the materials shown in the 4th and 5th columns when burned at. 1500 centigrade had zero as a, water absorption. It 'will further be noted I that at'1530 centigrade the material 'de- 0 flected by the present process but the vitrification point is aflecte It will be understood that the vitrifying referred to. herein" is a partial melting, though not a complete melting, whereby the particles forming the objects stick together in such a way as to make the article dense, the higher the degree of vitrification the more dense the object and therefore the more impervious to water.

lation between the percentage of Water abrmedso'that the deformation point is not For this reason, the percentage of water absorption can be taken V Witnesses: I

I the vitrifying point depends upon the i eness of the particles in the sol-condition which are collected and from which the objects to be burned are formed. However, it is found that the vitrifying point also depends upon. the nature of the electrolyte through the addition of which the matter in suspension is brought into a sol-condition. For instance, the vitrifying point will 1 be lowered less when ammonia 1s used as an electrolyte than when either sodium hydroxid or sodium silicateis used as the electrolyte. With equal settling duration, the vitrifying point of the same material can be lowered more or less through the ad dition of an electrolyte of more or less activity. v

I claim:-

1. The process of making ceramics having a desired degree of water absorption from I a substance which untreated deforms at the temperature of true vitrification wh1ch consists inpowderin'g the original substance,

suspending the same, bringing the same in,

sol-condition, permitting the solution to stand for an interval of time, collecting the said particles from the suspension and s1ntering the same. p I

2. The process of preparing for burnmg, material having a desired degree of water I absorption from a substance which untreated deforms at the temperature of true vitrification which consists in powdering the material, suspending the same, bringing the substance into sol-condition, permitting said substance to stand an interval of time, and

collecting the particles in suspension.

In testimony whereof I aflix my signature in presence of two. witnesses.

.- so e SCHWERIN.

JEAN GRUND, "CARL GRUND. 

